Learning and deployment of adaptive wireless communications

ABSTRACT

Methods, systems, and apparatus, including computer programs encoded on computer storage media, for training and deploying machine-learned communication over radio frequency (RF) channels. One method includes: determining an encoder and a decoder, at least one of which is configured to implement an encoding or decoding that is based on at least one of an encoder machine-learning network or a decoder machine-learning network that has been trained to encode or decode information over a communication channel; determining first information; using the encoder to process the first information and generate a first RF signal; transmitting, by at least one transmitter, the first RF signal through the communication channel; receiving, by at least one receiver, a second RF signal that represents the first RF signal altered by transmission through the communication channel; and using the decoder to process the second RF signal and generate second information as a reconstruction of the first information.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. application Ser. No.15/970,324, filed May 3, 2018, now allowed, which claims priority toU.S. Provisional Application No. 62/500,621 filed on May 3, 2017. Thedisclosures of the prior applications are considered part of and isincorporated by reference in the disclosure of this application.

TECHNICAL FIELD

The present disclosure relates to machine learning and deployment ofadaptive wireless communications, and in particular for radio frequency(RF) signals.

BACKGROUND

Radio frequency (RF) waveforms are prevalent in many systems forcommunication, storage, sensing, measurements, and monitoring. RFwaveforms are transmitted and received through various types ofcommunication media, such as over the air, under water, or through outerspace. In some scenarios, RF waveforms transmit information that ismodulated onto one or more carrier waveforms operating at RFfrequencies. In other scenarios, RF waveforms are themselvesinformation, such as outputs of sensors or probes. Information that iscarried in RF waveforms is typically processed, stored, and/ortransported through other forms of communication, such as through aninternal system bus in a computer or through local or wide-areanetworks.

SUMMARY

In general, the subject matter described in this disclosure can beembodied in methods, apparatuses, and systems for training and deployingmachine-learning networks to communicate over RF channels, andspecifically to encode and decode information for communication over RFchannels.

In one aspect, a method is performed by at least one processor to trainat least one machine-learning network to communicate over an RF channelThe method includes: determining first information; using an encodermachine-learning network to process the first information and generate afirst RF signal for transmission through a communication channel;determining a second RF signal that represents the first RF signalhaving been altered by transmission through the communication channel;using a decoder machine-learning network to process the second RF signaland generate second information as a reconstruction of the firstinformation; calculating a measure of distance between the secondinformation and the first information; and updating at least one of theencoder machine-learning network or the decoder machine-learning networkbased on the measure of distance between the second information and thefirst information. Other implementations of this aspect includecorresponding computer systems, apparatus, and computer programsrecorded on one or more computer storage devices, each configured tocause at least one operably connected processor to perform the actionsof the methods.

Implementations may include one or more of the following features. Themethod where updating at least one of the encoder machine-learningnetwork or the decoder machine-learning network based on the measure ofdistance between the second information and the first informationincludes: determining an objective function including the measure ofdistance between the second information and the first information;calculating a rate of change of the objective function relative tovariations in at least one of the encoder machine-learning network orthe decoder machine-learning network; selecting, based on the calculatedrate of change of the objective function, at least one of a firstvariation for the encoder machine-learning network or a second variationfor the decoder machine-learning network; and updating at least one ofthe encoder machine-learning network or the decoder machine-learningnetwork based on the at least one of the selected first variation forthe encoder machine-learning network or the selected second variationfor the decoder machine-learning network. The method where the measureof distance between the second information and the first informationincludes at least one of (i) a cross-entropy between the secondinformation and the first information, or (ii) a geometric distancemetric between the second information and the first information. Themethod where updating at least one of the encoder machine-learningnetwork or the decoder machine-learning network includes at least oneof: updating at least one encoding network weight or networkconnectivity in one or more layers of the encoder machine-learningnetwork, or updating at least one decoding network weight or networkconnectivity in one or more layers of the decoder machine-learningnetwork. The method where updating at least one of the encodermachine-learning network or the decoder machine-learning network furtherincludes: determining a channel mode, from among a plurality of channelmodes, that represents a state of the communication channel; andupdating at least one of the encoder machine-learning network or thedecoder machine-learning network based on the channel mode of thecommunication channel. The method where the encoder machine-learningnetwork and the decoder machine-learning network are jointly trained asan auto-encoder to learn communication over a communication channel, andwherein the auto-encoder includes at least one channel-modeling layerrepresenting effects of the communication channel on transmittedwaveforms. The method where the at least one channel-modeling layerrepresents at least one of (i) additive Gaussian thermal noise in thecommunication channel, (ii) delay spread caused by time-varying effectsof the communication channel, (iii) phase noise caused by transmissionand reception over the communication channel, or (iv) offsets in phase,frequency, or timing caused by transmission and reception over thecommunication channel. The method where at least one of the encodermachine-learning network or the decoder machine-learning networkincludes at least one of a deep dense neural network (DNN), aconvolutional neural network (CNN), or a recurrent neural network (RNN)including parametric multiplications, additions, and non-linearities.The method, further including: processing the first RF signal togenerate a first analog RF waveform that is input into the communicationchannel; receiving a second analog RF waveform as an output of thecommunication channel that represents the first analog RF waveformhaving been altered by the communication channel; and processing thesecond analog RF waveform to generate the second RF signal. The methodwhere the communication channel includes at least one of a radiocommunication channel, an acoustic communication channel, or an opticalcommunication channel. Implementations of the described techniques mayinclude hardware, a method or process, or computer software on acomputer-accessible medium.

In another aspect, a method is performed by at least one processor todeploy a learned communication system over an RF channel. The methodincludes: determining an encoder and a decoder, at least one of which isconfigured to implement an encoding or decoding that is based on atleast one of an encoder machine-learning network or a decodermachine-learning network that has been trained to encode or decodeinformation over a communication channel; determining first information;using the encoder to process the first information and generate a firstRF signal; transmitting, by at least one transmitter, the first RFsignal through the communication channel; receiving, by at least onereceiver, a second RF signal that represents the first RF signal alteredby transmission through the communication channel; and using the decoderto process the second RF signal and generate second information as areconstruction of the first information. Other implementations of thisaspect include corresponding computer systems, apparatus, and computerprograms recorded on one or more computer storage devices, eachconfigured to cause at least one operably connected processor to performthe actions of the methods.

Implementations may include one or more of the following features. Themethod, further includes: determining feedback information thatindicates at least one of (i) a measure of distance between the secondinformation and the first information, or (ii) channel state informationregarding the communication channel; and updating at least one of theencoder or the decoder based on the feedback information. The methodwhere updating at least one of the encoder or the decoder based on thefeedback information further includes: determining a channel mode, fromamong a plurality of channel modes, that represents a state of thecommunication channel based on the feedback information; and updating atleast one of the encoder or the decoder based on the channel mode of thecommunication channel. The method where the encoder implements anencoding mapping that is based on results of training an encodermachine-learning network and the decoder implements a decoding mappingthat is based on results of training a decoder machine-learning network,and where the encoder machine-learning network and the decodermachine-learning network have been jointly trained as an auto-encoder tolearn communication over a communication channel. The method, furtherincludes: processing the first RF signal to generate a first analog RFwaveform; using one or more transmit antennas to transmit the firstanalog RF waveform over the communication channel; using one or morereceive antennas to receive a second analog RF waveform that representsthe first analog RF waveform having been altered by the communicationchannel; and processing the second analog RF waveform to generate thesecond RF signal. Implementations of the described techniques mayinclude hardware, a method or process, or computer software on acomputer-accessible medium.

Another aspect includes a system including: at least one processor; andat least one computer memory coupled to the at least one processorhaving stored thereon instructions which, when executed by the at leastone processor, cause the at least one processor to perform operationsincluding: determining first information; using an encodermachine-learning network to process the first information and generate afirst RF signal for transmission through a communication channel;determining a second RF signal that represents the first RF signalhaving been altered by transmission through the communication channel;using a decoder machine-learning network to process the second RF signaland generate second information as a reconstruction of the firstinformation; calculating a measure of distance between the secondinformation and the first information; and updating at least one of theencoder machine-learning network or the decoder machine-learning networkbased on the measure of distance between the second information and thefirst information. Other implementations of this aspect includecorresponding computer systems, apparatus, and computer programsrecorded on one or more computer storage devices, each configured tocause at least one operably connected processor to perform the actionsof the methods.

Implementations may include one or more of the following features. Thesystem where updating at least one of the encoder machine-learningnetwork or the decoder machine-learning network based on the measure ofdistance between the second information and the first informationincludes: determining an objective function including the measure ofdistance between the second information and the first information;calculating a rate of change of the objective function relative tovariations in at least one of the encoder machine-learning network orthe decoder machine-learning network; selecting, based on the calculatedrate of change of the objective function, at least one of a firstvariation for the encoder machine-learning network or a second variationfor the decoder machine-learning network; and updating at least one ofthe encoder machine-learning network or the decoder machine-learningnetwork based on the at least one of the selected first variation forthe encoder machine-learning network or the selected second variationfor the decoder machine-learning network. The system where the measureof distance between the second information and the first informationincludes at least one of (i) a cross-entropy between the secondinformation and the first information, or (ii) a geometric distancemetric between the second information and the first information. Thesystem where updating at least one of the encoder machine-learningnetwork or the decoder machine-learning network includes at least oneof: updating at least one encoding network weight or networkconnectivity in one or more layers of the encoder machine-learningnetwork, or updating at least one decoding network weight or networkconnectivity in one or more layers of the decoder machine-learningnetwork. The system where updating at least one of the encodermachine-learning network or the decoder machine-learning network furtherincludes: determining a channel mode, from among a plurality of channelmodes, that represents a state of the communication channel; andupdating at least one of the encoder machine-learning network or thedecoder machine-learning network based on the channel mode of thecommunication channel. The system where the encoder machine-learningnetwork and the decoder machine-learning network are jointly trained asan auto-encoder to learn communication over a communication channel, andwhere the auto-encoder includes at least one channel-modeling layerrepresenting effects of the communication channel on transmittedwaveforms. The system where the at least one channel-modeling layerrepresents at least one of (i) additive Gaussian thermal noise in thecommunication channel, (ii) delay spread caused by time-varying effectsof the communication channel, (iii) phase noise caused by transmissionand reception over the communication channel, or (iv) offsets in phase,frequency, or timing caused by transmission and reception over thecommunication channel. The system where at least one of the encodermachine-learning network or the decoder machine-learning networkincludes at least one of a deep dense neural network (DNN) aconvolutional neural network (CNN), or a recurrent neural network (RNN)including parametric multiplications, additions, and non-linearities.The system where the operations further include: processing the first RFsignal to generate a first analog RF waveform that is input into thecommunication channel; receiving a second analog RF waveform as anoutput of the communication channel that represents the first analog RFwaveform having been altered by the communication channel; andprocessing the second analog RF waveform to generate the second RFsignal. The system where the communication channel includes at least oneof a radio communication channel, an acoustic communication channel, oran optical communication channel. Implementations of the describedtechniques may include hardware, a method or process, or computersoftware on a computer-accessible medium.

Another aspect includes a system including: at least one processor; andat least one computer memory coupled to the at least one processorhaving stored thereon instructions which, when executed by the at leastone processor, cause the at least one processor to perform operationsincluding: determining an encoder and a decoder, at least one of whichis configured to implement an encoding or decoding that is based on atleast one of an encoder machine-learning network or a decodermachine-learning network that has been trained to encode or decodeinformation over a communication channel; determining first information;using the encoder to process the first information and generate a firstRF signal; transmitting, by at least one transmitter, the first RFsignal through the communication channel; receiving, by at least onereceiver, a second RF signal that represents the first RF signal alteredby transmission through the communication channel; and using the decoderto process the second RF signal and generate second information as areconstruction of the first information. Other implementations of thisaspect include corresponding computer systems, apparatus, and computerprograms recorded on one or more computer storage devices, eachconfigured to cause at least one operably connected processor to performthe actions of the methods.

Implementations may include one or more of the following features. Thesystem where the operations further include: determining feedbackinformation that indicates at least one of (i) a measure of distancebetween the second information and the first information, or (ii)channel state information regarding the communication channel; andupdating at least one of the encoder or the decoder based on thefeedback information. The system where updating at least one of theencoder or the decoder based on the feedback information furtherincludes: determining a channel mode, from among a plurality of channelmodes, that represents a state of the communication channel based on thefeedback information; and updating at least one of the encoder or thedecoder based on the channel mode of the communication channel. Thesystem where the encoder implements an encoding mapping that is based onresults of training an encoder machine-learning network and the decoderimplements a decoding mapping that is based on results of training adecoder machine-learning network, and where the encoder machine-learningnetwork and the decoder machine-learning network have been jointlytrained as an auto-encoder to learn communication over a communicationchannel. The system where the operations further include: processing thefirst RF signal to generate a first analog RF waveform; using one ormore transmit antennas to transmit the first analog RF waveform over thecommunication channel; using one or more receive antennas to receive asecond analog RF waveform that represents the first analog RF waveformhaving been altered by the communication channel; and processing thesecond analog RF waveform to generate the second RF signal.Implementations of the described techniques may include hardware, amethod or process, or computer software on a computer-accessible medium.

Other implementations of this and other aspects include correspondingsystems, apparatuses, and computer programs, configured to perform theactions of the methods, encoded on computer storage devices. A system ofone or more computers can be so configured by virtue of software,firmware, hardware, or a combination of them installed on the systemthat in operation cause the system to perform the actions. One or morecomputer programs can be so configured by virtue of having instructionsthat, when executed by data processing apparatus, cause the apparatus toperform the actions.

All or part of the features described throughout this application can beimplemented as a computer program product including instructions thatare stored on one or more non-transitory machine-readable storage media,and that are executable on one or more processing devices. All or partof the features described throughout this application can be implementedas an apparatus, method, or electronic system that can include one ormore processing devices and memory to store executable instructions toimplement the stated functions.

The details of one or more implementations of the subject matter of thisdisclosure are set forth in the accompanying drawings and thedescription below. Other features, aspects, and advantages of thesubject matter will become apparent from the description, the drawings,and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a radio frequency (RF) system thatimplements a machine-learning encoder and decoder to perform learnedcommunication over one or more RF channels;

FIG. 2 illustrates an example of a network structure of machine-learningencoder and decoder networks that may be implemented in an RF system toperform learned communication over RF channels;

FIG. 3 illustrates an example of a training an RF system that implementsmachine-learning encoder and decoder networks to learn encoding anddecoding over RF channels;

FIG. 4 is a flowchart illustrating an example method of training an RFsystem that implements machine-learning encoder and decoder networks tolearn encoding and decoding over RF channels;

FIG. 5 illustrates examples of basis functions that may be learned andutilized by an encoder machine-learning network and/or decodermachine-learning network to communicate over RF channels;

FIG. 6 illustrates examples of a transmitted RF signal and a received RFsignal that may be learned by an encoder machine-learning network and adecoder machine-learning network for communicating over an RF channel;

FIG. 7 illustrates an example of deploying a system that implements anencoder and decoder that utilize encoding and/or decoding techniquesbased on results of training encoding and decoding machine-learningnetworks to perform learned communication over a real-world RF channel;

FIG. 8 is a flowchart illustrating an example method of deploying anencoder and decoder that utilize encoding and/or decoding techniquesbased on results of training encoding and decoding machine-learningnetworks to perform learned communication over a real-world RF channel;and

FIG. 9 is a diagram illustrating an example of a computing system thatmay be used to implement one or more components of a system thatperforms learned communication over RF channels.

DETAILED DESCRIPTION

Systems and techniques are disclosed herein that enable machine learningand deployment of communication over an impaired RF channel. In someimplementations, at least one machine-learning network is trained toencode information as a signal that is transmitted over a radiotransmission channel, and to decode a received signal to recover theoriginal information. The training may be designed to achieve variouscriteria, such as low bit error rate, low power, low bandwidth, lowcomplexity, performing well in particular regimes such as at a lowsignal to noise (SNR) ratio or under specific types of channel fading orinterference, and/or other criteria. The results of training suchmachine-learning networks may then be utilized to deploy real-worldencoders and decoders in communication scenarios to encode and decodeinformation over various types of RF communication media. In someimplementations, further learning and adaptation of the encoder anddecoder may be implemented during deployment, based on feedbackinformation. These encoders and decoders may replace or augment one ormore signal processing functions such as modulation, demodulation,mapping, error correction, or other components which exist in thosesystems today.

The disclosed implementations present a novel approach to how digitalradio systems are designed and deployed for radio communicationsapplications. For example, the disclosed implementations may helpimprove a typically slow and incremental process of radio signalprocessing engineering, and instead enable a new way of designing,constructing, and realizing radio communications systems. Byimplementing machine-learning networks that may be trained to learnsuitable encoding and decoding techniques for different types ofcommunication media, techniques disclosed herein offer variousadvantages, such as improved power, resiliency, and complexityadvantages over presently available systems. In some scenarios, this canbe especially important for communications channels which have verycomplex sets of effects which are hard to model, or hard to optimize forusing other approaches.

Implementations disclosed herein may be applied to a wide range of radiocommunication systems, such as cellular, satellite, optical, acoustic,physical, emergency hand-held, broadcast, point-to-point, Wi-Fi,Bluetooth, and other forms of radio that undergo transmissionimpairments. Channel impairments may include, for example, thermalnoise, such as Gaussian-like noise, to more complex impairments such asmulti-path fading, impulse noise, spurious or continuous jamming,interference, distortion, hardware effects, and other impairments.

The encoder and decoder may implement encoding and decoding techniquethat are learned from one or more machine-learning networks that havebeen trained to learn suitable input-output encoding and decodingmappings based on one or more objective criteria. For example, themachine-learning networks may be artificial neural networks. Duringtraining, the machine-learning networks may be adapted through selectionof model architecture, weights, and parameters in the encoder and/or thedecoder to learn encoding and decoding mappings. The encoding anddecoding machine-learning networks may be trained jointly or may betrained iteratively.

For example, an encoder machine-learning network and decodermachine-learning network may be implemented as an autoencoder, in whichthe encoder network and decoder network are jointly optimized. In someimplementations, the autoencoder may be trained by modeling the effectsof an impaired channel as one or more channel-modeling layers, such asstochastic layers which may include regularization layers (e.g.regularization layers, transforming layers, variational layers/samplers,noise layers, mixing layers, etc.) in the autoencoder network or asanother set of differentiable functions representing the behavior of awireless channel. The layers that model the channel may form aregularization function across random behavior of a channel.

During training, an encoder machine-learning network and decodermachine-learning network may be trained to perform unsupervised, orpartially supervised, machine learning to determine techniques fortransmitting and receiving information over an impaired channel.Therefore, in some scenarios, rather than being reliant uponpre-designed systems for error correction, modulation, pre-coding, andshaping, the disclosed implementations herein may adaptively learntechniques for encoding information into waveforms that are transmittedover a channel, as well as techniques for decoding received waveformsinto reconstructed information. The encoder machine-learning networkand/or decoder machine-learning network may be trained on real orsimulated channel conditions. Encoders and/or decoders that utilizeresults of training such machine-learning networks may further beupdated during deployment, thus providing advantages in adapting todifferent types of wireless system requirements, and in some casesimproving the throughput, error rate, complexity, and power consumptionperformance of such systems.

As such, regardless of the type of RF channel or RF channel impairment,implementations disclosed herein can provide broadly applicabletechniques for learning representations of information that enablereliable communication over impaired RF channels. Depending on theconfiguration of the training system and data sets and channel modelsused, such machine-learning communication techniques can specialize inperformance for a narrow class of conditions, signal or channel types,or may generalize and optimize performance for a wide range of signal orchannel types or mixtures of one or more signals or channels.

FIG. 1 illustrates an example of a radio frequency (RF) system 100 thatimplements an encoder and decoder to perform learned communication overone or more RF channels. The system 100 includes both an encoder 102 anda decoder 104 that implement encoding and decoding techniques that werelearned by machine learning networks to communicate over an impaired RFchannel 106.

In scenarios of training, the encoder 102 include a machine-learningnetwork that learns how to represent the input information 108 as atransmitted signal 112 for transmission over the channel 106.Analogously, during training, the decoder 104 includes amachine-learning network that learns how to decode a received signal 114into reconstructed information 110 that approximates the original inputinformation 108. During training, the encoder 102 and/or decoder 104 maybe trained by a network update process 116. The encoder 102 and decoder104 may be trained to achieve various types of objective functions, suchas a measure of reconstruction error, a measure of computationalcomplexity, bandwidth, latency, power, or various combinations thereforand other objectives. Further details of training are described below,for example with reference to FIG. 3.

In scenarios of deployment, the encoder 102 and decoder 104 mayimplement encoding and decoding techniques that were previously learnedfrom training, or may be (further) trained during deployment. Theencoder 102 and decoder 104 may be deployed in various applicationscenarios to perform communication, using the encoding and decodingrepresentations that were learned during training. In someimplementations, the encoder 102 and/or decoder 104 may be furtherupdated during deployment based on real-time performance results such asreconstruction error, power consumption, delay, etc. Further details ofdeployment are described below, for example with reference to FIG. 7. Inthese cases, error feedback of loss functions may occur in someinstances via a communications bus, or a protocol message within thewireless system which can be used to update the encoder 102 and/ordecoder 104, along with information to help characterize the response ofthe channel 106.

The input information 108 and reconstructed information 110 may be anysuitable form of information that is to be communicated over a channel,such as a stream of bits, packets, discrete-time signals, orcontinuous-time waveforms. Implementations disclosed herein are notlimited to any particular type of input information 108 andreconstructed information 110, and are generally applicable to learnencoding and decoding techniques for communicating a wide variety oftypes of information over the RF channel 106.

In some implementations, the encoder 102 and decoder 104 employ one ormore signal processing operations, which are suited to the type of RFcommunication domain. As examples, the encoder 102 and/or decoder mayimplement filtering, modulation, analog-to-digital (A/D) ordigital-to-analog (D/A) conversion, equalization, or other signalprocessing methods that may be suitable for a particular types of RFsignals or communication domains. In some implementations, the encoder102 and/or decoder 104 may implement one or more transmit and receiveantennas, and other hardware or software suitable for transmittingsignals 112 and receiving signals 114 over the RF channel 106.

Therefore, in such scenarios, as shown in the example of FIG. 1, thetransmitted signal 112 and received signal 114 may represent actual RFwaveforms that are transmitted and received over the RF channel 106through one or more antennas. Thus, the encoder 102 and decoder 104represent generalized mappings between information 108/110 and RFwaveforms 112/114.

By contrast, in some implementations, the system 100 may implementsignal processing and RF transmission/reception processes separatelyfrom the encoder 102 and decoder 104. In such implementations, one ormore signal transmission and/or signal reception components, such asfiltering, modulation, A/D or D/A conversion, single or multipleantennas, etc., may be represented as part of the channel 106. Theimpairments in the channel 106 may therefore includetransmitter/receiver effects, such as filtering impairments, additivenoise, or other impairments in the transmitter and/or receivercomponents. Therefore, in such scenarios, the transmitted signal 112 andreceived signal 114 represent intermediate representations ofinformation 108/110, and the channel 106 represents a generaltransformation of those intermediate representations of information toand from actual RF waveforms that are transmitted and received over anRF medium. For example, the transmitted signal 112 and received signal114 may represent basis coefficients for RF waveforms, time-domainsamples of RF waveforms, distributions over RF waveform values, or otherintermediate representations that may be transformed to and from RFwaveforms.

In scenarios of training, the reconstructed information 110 may becompared with the original information 108, and the encoder 102 and/orthe decoder 104 may be trained (updated) based on results of thereconstruction. In some implementations, updating the encoder 102 and/ordecoder 104 may also be based on other factors, such as computationalcomplexity of the machine-learning networks (which can be measured, forexample, by the number of parameters, number of multiplies/adds,execution time, Kolmogorov complexity, or otherwise), transmissionbandwidth or power used to communicate over the channel 106, or variouscombinations thereof and other metrics.

In some implementations, the encoder 102 and the decoder 104 may includeartificial neural networks that consist of one or more connected layersof parametric multiplications, additions, and non-linearities. In suchscenarios, updating the encoder 102 and/or decoder 104 may includeupdating weights of the neural network layers, or updating connectivityin the neural network layers, or other modifications of the neuralnetwork architecture, so as to modify a mapping of inputs to outputs.

The encoder 102 and the decoder 104 may be configured to encode anddecode using any suitable machine-learning technique. In general, theencoder 102 may be configured to learn a mapping from input information108 into a lower-dimensional or higher-dimensional representation as thetransmitted signal 112. Analogously, the decoder 104 may be configuredto learn a reverse mapping from a lower-dimensional orhigher-dimensional received signal 114 into the reconstructedinformation 110.

As an example, the mappings that are implemented in the encoder 102 anddecoder 104 may involve learning a set of basis functions for RFsignals. In such scenarios, for a particular set of basis functions, theencoder 102 may transform the input information 108 into a set of basiscoefficients corresponding to those basis functions, and the basiscoefficients may then be used to generate a transmitted RF waveform (forexample, by taking a weighted combination of the basis functionsweighted by the basis coefficients). Analogously, the decoder 104 maygenerate the reconstructed information 110 by generating a set of basiscoefficients from a received RF waveform (for example by takingprojections of the received RF waveform onto the set of basisfunctions). The basis functions themselves may be any suitableorthogonal or non-orthogonal set of basis functions, subject toappropriate constraints on energy, amplitude, bandwidth, or otherconditions.

During deployment, in some implementations, the encoder 102 and/ordecoder 104 may utilize simplified encoding and decoding techniquesbased on results of training machine-learning networks. For example, theencoder 102 and/or decoder 104 may utilize approximations or compactlook up tables based on the learned encoding/decoding mappings. In suchdeployment scenarios, the encoder 102 and/or decoder 104 may implementmore simplified structures, rather than a full machine-learning network.For example, techniques such as distillation may be used to trainsmaller machine-learning networks which perform the same signalprocessing function. Further discussion of such deployment scenarios isprovided in regards to FIG. 7, below.

In some implementations, the encoder 102 and/or decoder 104 may includeone or more fixed components or algorithms that are designed tofacilitate communication over RF channels, such as expert synchronizers,equalizers, etc. As such, during training, the encoder 102 and/ordecoder 104 may be trained to learn encoding/decoding techniques thatare suitable for such fixed components or algorithms.

RF signals that are transmitted and received by system 100 may includeany suitable radio-frequency signal, such as acoustic signals, opticalsignals, or other analog waveforms. The spectrum of RF signals that areprocessed by system 100 may be in a range of 1 kHz to 300 GHz. Forexample, such RF signals include very low frequency (VLF) RF signalsbetween 1 kHz to 30 kHz, low frequency (LF) RF signals between 30 kHz to300 kHz, medium frequency (MF) RF signals between 300 kHz to 1 MHz, highfrequency (HF) RF signals between 1 MHz to 30 MHz, and higher-frequencyRF signals up to 300 GHz.

FIG. 2 illustrates an example of a network structure 200 ofmachine-learning encoder network and decoder networks that may beimplemented in an RF system to perform learned communication over RFchannels.

The network structure 200 uses one or more layers that form an encodernetwork 202 and a decoder network 204. The output of each layer is usedas input to the next layer in the network. Each layer of the networkgenerates an output from a received input in accordance with currentvalues of a respective set of parameters. For example, in someimplementations, the encoder network 202 and/or decoder network 204 mayinclude a plurality of networks that may be collectively or iterativelytrained. As such, the network input 208 in FIG. 2 may be the originalinformation (e.g., input information 108 in FIG. 1, above), or may be anoutput of previous one or more layers in the encoder network 204.Analogously, the network output 210 may represent the reconstructedinformation (e.g., reconstructed information 110 in FIG. 1, above), ormay be an input into subsequent one or more layers in the decodernetwork 204. In some instances, networks may not be sequential innature, leveraging connections between various layers or neurons whichbypass or route through a plurality of possible architectures.

During training, the encoder network 202 and/or decoder network 204 maybe trained to learn encoding and/or decoding techniques forcommunicating over various types of RF channels. During deployment, theencoder network 202 and/or decoder network 204 (having been trained) maybe implemented in an encoder and/or decoder. Alternatively, in somescenarios of deployment, a deployed encoder and decoder may utilizesimplified encoding and decoding mapping based on results of trainingthe encoder network 202 and/or decoder network 204. In the latterscenario, the encoder network 202 and/or decoder network 204 is onlyutilized during training, and provide learned encoding and/or decodingtechniques that may be utilized in more simplified encoders and decodersthat are deployed in real-world systems. Further discussion of suchsimplified deployment scenarios is provided in regards to FIG. 7, below.

In the example of FIG. 2, the encoder network 202 and decoder network204 are implemented using a neural network structure 200 that isconfigured as an autoencoder. In the scenario of an autoencoderstructure, the encoder and decoder are jointly trained to learn bestrepresentations of information for communication over the channel 206.In general, however, the network structure 200 may be configured asseparate networks in the encoder network 202 and decoder network 204,which may be jointly or iteratively trained. During training, theencoder network 202 and/or decoder network 204 may be updated by anetwork update process 216.

In general, the encoder network 202 and/or decoder network 204 mayinclude one or more collections of multiplications, divisions, andsummations or other operations of inputs and intermediate values,optionally followed by non-linearities (such as rectified linear units,sigmoid function, or otherwise) or other operations (e.g.,normalization), which may be arranged in a feed-forward manner or in amanner with feedback and in-layer connections (e.g., a recurrent neuralnetwork (RNN) where sequences of training information may be used insome instances). For example, a recurrent neural network may be along-short term memory (LSTM) neural network that includes one or moreLSTM memory blocks, or a quasi-recurrent neural network (QRNN) whichcombines elements of convolutional networks with recurrent networks.

Parameters and weight values in the network may be used for a singlemultiplication, as in a fully connected deep dense neural network (DNN),or they may be “tied” or replicated across multiplelocations within thenetwork to form one or more receptive fields, such as in a convolutionalneural network, a dilated convolutional neural network, a residualnetwork unit, or similar. A collection of one or more of these layersmay constitute both the encoder 202 and the decoder 204, as shown in theexample of FIG. 2. The specific structure for the networks may beexplicitly specified at design time, or may be selected from a pluralityof possible architecture candidates to ascertain the best performingcandidate.

In some implementations, the encoder network 202 may include an outputlayer that includes a linear regression layer. The decoder network 204may include at least one of (i) an output layer that includes a linearlayer for regression of reconstructed information 210 in decoding thereceived RF signal 214, or (ii) a sigmoid or hard-sigmoid activationlayer for probability regression or slicing of the received RF signal214, or (iii) an activation of a combination of sigmoid expressions suchas a SoftMax or hierarchical SoftMax which can compute a probabilisticexpression such as a pseudo-likelihood of a discrete message or set ofbits.

In some implementations, the encoder network 202 and/or decoder network204 may include one or more layers that implement fixed communicationsalgorithms, such as synchronization, equalization, etc. As such, in somescenarios, the encoder network 202 and/or decoder network 204 may betrained and deployed to learn suitable encoding and/or decodingtechniques based on such fixed layers in the networks. Therefore, ingeneral, the network structure 200 disclosed herein enables flexibledesign and training of the encoder network 202 and decoder network 204,for example by incorporating one or more existing communicationalgorithms that may be deployed in real-world systems in conjunctionwith machine-learning techniques to optimize around those fixedalgorithms.

The example of FIG. 2 shows only one possible implementation of anetwork structure that may be implemented. In general, implementationsare not limited to these specific types of layers, and otherconfigurations of layers and non-linearities may be used, such as dense,fully connected, and/or DNN layers, including rectified linear-unit(ReLU), sigmoid, tan h, and others. The network structure 200 uses theselayers to predict an output 210 for a received input 208. In someimplementations, a linear regression layer may be implemented on theoutput of the encoder 202 and a linear layer on the output of thedecoder 204 (for soft decoding), or a hard-sigmoid activation on theoutput of the decoder 204 (for hard decoding).

A transmitted signal 212, created by the encoder 202, may be the actualRF waveform in analog form, or may be a series of radio samples in time,frequency, or any other signal representation basis, or may be anintermediate representation (e.g., RF samples, basis coefficients,distributions over RF waveform values, etc.), for mapping the inputinformation 208 into an RF waveform for transmission over the channel206. Analogously, the received signal 214 may be the actual received RFwaveform in analog form, or may be an intermediate representation (e.g.,RF samples, basis coefficients, distributions over RF waveform values,etc.), for mapping a received RF waveform into the reconstructedinformation 210. For example, in the scenario where the encoder 202 anddecoder 204 are implemented as a variational auto-encoder, thetransmitted RF signal 212 and received RF signal 214 may representdistributions over RF waveform values.

The network structure 200 may also include one or more channel-modelinglayers 207, which may be stochastic layers (e.g., regularizationlayers). In some instances, the channel-modeling layers 207 may have atleast one of weight regularization on convolutional network layerweights, activity regularization on dense network layer activations, orother stochastic impairments on activations or weights, such as dropout.In some instances, or in addition to these, the layers may performadditional approximation of non-linearities present in a channel system(such as amplifier or RF component behaviors), or they may leveragevariational layers such as sampling from a random distribution specifiedby or parameterized by weights or activations.

In some implementations, the channel-modeling layer(s) 207 may modelimpairment effects in the channel 206, which may be include varioustypes of impairments in an RF medium and/or transmission and receptioncomponents. Such channel-modeling layers 207 may be implemented duringtraining of the network structure 200, in which case thechannel-modeling layer(s) 207 may be implemented as one or more layersin an overall auto-encoder structure to represent impairment effects ofthe channel 206. During evaluation or deployment over a real RFchannels, the channel 206 would be a real-world communication channel(including possible transmitter and/or receiver effects), and thecorresponding channel-modeling layers 207 would be removed fromdeployment, with only the network layers of the encoder 202 and thedecoder 204 being deployed on the real channel 206.

In general, however, channel-modeling layers 207 may be implemented forvarious in different parts of the network structure 200 for variousreasons, such as to prevent over-fitting, or to implement dropout, suchas a penalty on the convolutional layer weights, to encourage minimumenergy bases, or to implement a penalty on dense layer activations toencourage sparsity of solutions, or to improve generalization of thesystem to unseen conditions or channel states or behaviors.

In scenarios of using channel-modeling layer(s) 207 to model the channel206 during training, the network structure 200 may implementdomain-specific regularization to model RF channel impairment effects.For example, the channel-modeling layer(s) 207 may model different typesof impairments that occur during over-the-air transmission in a wirelessRF system, such as additive Gaussian thermal noise, unknown time andrate of arrival, carrier frequency and phase offset, fading, hardwaredistortions, interference, and/or delay spread in the received signal.

Such channel-modeling layers 207, such as Gaussian noise and dropout,may be used during training and removed during evaluation or deploymentover real channels. In radio communications, additive noise, such asAdditive White Gaussian Noise (AWGN) may be modeled by adding areal-valued Gaussian random variable to different signal components,which may be signal basis functions (e.g., in-phase (I) and quadrature(Q) components), that are passed through the channel. In someimplementations, a normalization layer may be implemented before theAWGN effects, which normalizes the average power incoming activations,for example to a normalized value equal to 1. This form of constraintcan be applied to the encoder 202 to enforce a wide range of possiblewaveform design criteria, such as a maximum power, minimum power, meanpower, mean amplitude, peak to average power ratio, or a wide range ofproperties of the transmit waveform which may be used as a hardconstraint. Alternatively, similar such waveform design objectives maybe included as soft constraints which are combined into the network'sloss function during training, as further discussed in regards to FIG.3, below.

Channel-modeling layers 207 may also be implemented to model unknowntime and rate of arrival, for example by applying a random or a prioriunknown shift and scaling in the time domain, which may model scenariosin which radio propagation times vary and clocks on distributed radiosystems are not synchronized. These effects may be modeled, for example,by a random time shift and a random time-dilation rate that haveGaussian distributions.

As other examples of channel-modeling layers 207, carrier frequency andphase offset may be modeled as rotations in signal components, which maybe signal basis functions. In some implementations, sampling may beperformed using complex baseband representations, in which case unknownoffsets in center frequency and absolute phase of arrival due tounsynchronized oscillators on transmitter and receiver, as well asDoppler shift, may result in static or linear polar mixing of thedifferent signal components. To simulate a real system and to improvegeneralization, such channel-modeling layers 207 may randomly select aphase and a frequency offset, or a linear phase ramp based on anexpected center frequency offset error due to independent driftingoscillators.

As yet another example of channel-modeling layers 207, delay spread inthe received signal may be modeled to simulate the arrival of numerousdelayed and phase shifted copies of a signal arriving at the receiver.Since this is simulated as a linear system and we assume stability overa single sample time window, we can choose a random non-impulsivechannel delay spread filter and convolve it with the input signal toobtain an output which has been spread in time linearly according to arandom channel response. This assumption may be appropriate, forexample, in scenarios where the signal window is smaller than thechannel coherence time. In scenarios where the signal window larger thana channel coherence time, the channel progression may be modeled as asequence with some degree of correlation, and the network 200 may learntechniques correcting the sequence of delay spread modes.

Such delay spread and coherence time may vary in different types ofcommunication systems, including wire-line and space-based wirelesssystems which can sometimes have very short impulsive channel responses,or high frequency and dense multi-path wireless systems which can havelong delay spreads. In some implementations, the delay spread is modeledas a channel-modeling layer 207 that implements one or more convolutionsor filtering operations on the transmitted RF signal.

In some implementations, the network structure 200 may be utilized withone or more fixed transmission and/or receiving techniques, and mayadapt the layers of the encoding network 202 and/or the decoding network204 to learn encoding and decoding operations that are suitable forthose fixed transmission/reception components. For example, in somescenarios the network structure 200 may employ fixed filtering,sampling, modulation, equalization, subcarrier assignment, referencesignal insertion, encoding, or other transmission/reception techniques,and may learn suitable network layer parameters or network structuresthat adapt the overall communication system to best utilize those fixedcomponents.

A general design objective for the network structure 200 may be toobtain a desired reconstruction performance for the reconstructedinformation 210, subject to other objectives or constraints. Forexample, certain realizations of the system may favor reduced powerand/or bandwidth, other improved properties of the RF signalstransmitted over the channel, or improved computational complexity. Assuch, the system may evaluate a trade-off between these objectives,which may be used in order to help determine the specific architectureused for encoding, decoding, or other signal inference tasks.

FIG. 3 illustrates an example of a training an RF system 300 thatimplements machine-learning encoder and decoder networks to communicateover RF channels. The system 300 includes an encoder network 302 and adecoder network 304 that are trained to communicate over the channel306. The training illustrated in FIG. 3 may be implemented prior todeployment, or in some scenarios may be incorporated as part ofdeployment, for example to further update and refine the encoder network302 and decoder network 304 based on real-world performance.

In some implementations, the encoder network 302 and decoder network 304may be utilized for training to learn suitable encoding and decodingmappings, and such mappings may be implemented in a deployed systemusing more simplified encoders and decoders. For example, a deployedsystem may utilize using lookup tables at the encoder and distance-basedmetrics at the decoder, or other simplified forms of encoding anddecoding, that are designed based on results of training the encodernetwork 302 and decoder network 304. Further discussion of suchsimplified deployment scenarios is provided in regards to FIG. 7, below.

The channel 306 that is implemented during training may be a model of anRF channel that is obtained via simulation and/or based on real-world RFchannel data. For example, in some implementations, training may beginwith a simulated channel model and train the encoder network 302 anddecoder network 304 based on simulated propagation models reflecting areal world propagation environment or emitter data. The encoder network302 and decoder network 304 may then be further trained against a realchannel where hardware is used with a training feedback loop.

In some implementations, the model of the channel 306 may includeeffects of transmitter and receiver components, such as filtering,modulation, etc. For example, in scenarios where a simulated channel isused for training, an analytic channel impairment model may be utilizedthat fits a specific set of hardware/software and wireless deploymentconditions. As such, the training in FIG. 3 may train the encodernetwork 302 and decoder network 304 to operate under different channelconditions, as well as for different real-world transmitter and receiverscenarios.

During training, the encoder network 302 and decoder network 304 mayeither be jointly trained or iteratively trained. For example, theencoder network 302 and the decoder network 304 may be jointly trainedas an auto-encoder (as described in regards to FIG. 2, above). In someimplementations, the encoder network 302 and decoder network 304 may beseparately trained. In such scenarios, one of the networks may be fixed,either by previous training or by a transmission/reception scheme, whilethe other network is trained to learn an encoding/decoding strategy thatis appropriate for the fixed counterpart network.

For example, the encoder network 302 may be fixed to generate aparticular mapping of input information 308 to transmitted RF signals312, and the decoder network 304 may be trained to learn a mapping fromthe received RF signal 314 to reconstructed information 310 that is bestsuited for the fixed encoder 302. In some implementations, the inputinformation 308 may be represented by training data that is utilized fortraining purposes. The training data may have a different form than theinput information 308, but nonetheless may represent the inputinformation 308 for purposes of training. In such scenarios, the encodernetwork 302 may processes the training data that represents the firstinformation, and the decoder network 304 may generate reconstructedinformation 310 as a reconstruction of the first information 308represented by the training data.

The system 300 may compute a loss function 318 between the originalinput information 308 and the reconstructed information 310. The lossfunction 318 may be any suitable measure of distance between the inputinformation 308 and reconstructed information 310, such ascross-entropy, mean squared error, or other geometric distance metric(e.g., MAE). In some implementations, the loss function 318 may combineseveral geometric, entropy based, and/or other classes of distancemetrics into an aggregate expression for distance or loss.

In some implementations, additional loss terms may be used in the lossfunction 318 in combination with such primary loss terms, for example toaccomplish secondary objectives (e.g., to reduce interference imposedupon a secondary receiver, or to improve favorable signal propertiessuch as peak to average power ratio (PAPR)).

In addition to achieving an objective that includes the loss function318, the system 300 may also be configured to achieve an objectiverelated to other performance measures, such as power, bandwidth,complexity, or other performance metrics that are relevant forcommunication. In some implementations, the system 300 may be configuredto achieve a desired trade-off between different performance metrics.For example, achieving such a trade-off may be implemented using anobjective function that combines different metrics, for example as aweighted combination of the metrics. In addition or as an alternative,this trade-off may be achieved by selecting a model according to userpreferences or application specifications. In addition or as analternative, the system 300 may implement one or more hard constraintson performance metrics, such as constraints on power, bandwidth,reconstruction error, etc.

In some implementations, a network update process 316 may update theencoder network 302 and/or decoder network 304 based on the variousperformance metrics. This updating may include updates to the networkarchitectures, parameters, or weights of the networks in the encodernetwork 302 and/or decoder network 304. For example, the updating mayinclude updating weights or parameters in one or more layers of thenetworks, selecting machine-learning models for the encoder network 302and decoder network 304, or selecting a specific network architecture,such as choice of layers, layer-hyperparameters, or other networkfeatures. As discussed, updating may be implemented on the encodernetwork 302 and decoder network 304 in a joint or iterative manner, orindividually (as in the case where one of the networks is fixed).

As discussed above, the updates performed by network update process 316may be performed during training to learn suitable encoding and decodingtechniques prior to deployment, and/or may be performed duringdeployment (if a deployed encoder and/or decoder implementmachine-learning networks) to further update the encoder network 302and/or decoder network 304 based on real-world deployment performanceresults.

In some implementations, the network update process 316 may update theencoder network 302 and/or decoder network 304 to achieve a desiredobjective function, which may include the loss function 318 and otherperformance metrics discussed above. In some implementations, thenetwork update process 316 may utilize an optimization method such asone of evolution, gradient descent, stochastic gradient descent, orother solution technique.

As an example of gradient-based updates, the network update process 316may calculate a rate of change of the objective function relative tovariations in the encoder network 302 and/or decoder network 304, forexample by calculating or approximating a gradient of the objectivefunction. Such variations may include, for example, variations in theweights of one or more network layers, as shown in the example of FIG.3, or other network architecture choices. In scenarios where the channel306 is based on real RF channel data and does not have a closed formgradient solution, an approximate method may be used to estimate thegradient of the objective function.

Based on the calculated rate of change of the objective function, thenetwork update process 316 may determine a first variation for theencoder network 302 and/or a second variation for the decoder network304. These variations may be computed, for example, using StochasticGradient Descent (SGD) style optimizers, such as Adam, AdaGrad, NesterovSGD, or others. In some implementations, these variations may becomputed using other scalable methods for direct search, such asevolutionary algorithms or particle swarm optimizations.

Once the variations have been determined, the network update process 316then applies those variations to the encoder network 302 and/or thedecoder network 304. For example, the network update process 316 mayupdate at least one encoding network weight in one or more layers of theencoder network 302, and/or at least one decoding network weight in oneor more layers of the decoder network 304.

In general, updating the encoder network 302 and decoder network 304 isnot limited to updating network weights, and other types of updates maybe implemented. For example, updating the encoder network 302 and thedecoder network 304 may include selecting a machine-learning model forthe encoder network 302, from among a plurality of encoding models, andselecting a machine-learning model for the decoder network 304, fromamong a plurality of decoding models. In such implementations, selectingmachine-learning models may include selecting a specific networkarchitecture, such as choice of layers, layer-hyperparameters, or othernetwork features.

The encoder network 302 and/or decoder network 304 may be trained overvarious training models of the channel 306, which may be of the sametype or of different types of channel models. Depending on thecomposition of the set of models for channel 306, the encoder network302 and decoder network 304 may be optimized to communicate over acertain type of RF channel or a wide range of different types of RFchannels.

In some implementations, the model of channel 306 may be categorizedinto a number of different modes. During training, the encoder network302 and/or decoder network 304 may be trained on the different modes ofthe channel 306. For each of these modes, the encoder network 302 and/ordecoder network 304 may learn suitable encoding and/or decodingtechniques for the different modes. The different modes of the channel306 may represent any suitable categorization of channel condition, suchas level of noise, SNR, delay spread, rate of channel variations,bandwidth, etc.

In some implementations, instead of the channel 306 being a simulatedchannel, a real channel may be used to train the encoder network 302and/or decoder network 304. In such implementations, additionaltransmission and reception components (either hardware or software) maybe implemented to transmit and receive analog RF waveforms over the realchannel. Such transmit and receive components may be implemented eitherin the encoder network 302 and decoder network 304, or their effects maybe included in the channel effects that are accounted for in the modelof the channel 306. As such, the training in FIG. 3 may be performedover any suitable channel 306, whether simulated or real, to train theencoder network 302 and decoder network 304 to learn suitable encodingand decoding techniques.

During training, the encoder network 302 may be configured to learn amapping from input information 308 into a transmitted RF signal 312.Analogously, the decoder network 304 may be configured to learn areverse mapping from a received RF signal 314 into reconstructedinformation 310. As discussed above, the transmitted RF signal 312 andreceived RF signal 314 may represent analog RF waveforms that aretransmitted and received over an RF channel, or may representintermediate representations (e.g., samples of RF waveforms,coefficients of basis functions, distributions over RF waveforms, etc.)that are transformed to and from analog RF waveforms through processingby one or more other components, such as filters, modulators,equalizers, etc. For example, in the scenario where the encoder network302 and decoder network 304 are implemented as a variationalauto-encoder (as discussed in regards to FIG. 2, above), the RF signals212 and 214 may represent distributions over RF waveform values. Ingeneral, the transmitted RF signal 312 and received RF signal 314 mayrepresent any suitable RF signal representations that are learned by theencoder network 302 and decoder network 304 for encoding and decodinginformation over a particular channel or class of channels.

In some implementations, the encoding and decoding mappings may involvea set of basis functions. The basis functions may be used by the encodernetwork 302 to transform the input information 308 into the transmittedRF signal, which may be a set of basis coefficients, or an RF waveformthat is a weighted combination of basis functions, or other suitablerepresentation using a particular set of basis functions. Analogously,the decoder network 304 may use the same set of basis functions toprocess the received RF signal 314 to generate the reconstructedinformation 310, for example by taking projections of the RF signal 314onto the set of basis functions to generate basis coefficients, or inthe scenario where the RF signal 314 is itself a set of basiscoefficients, by transforming the basis coefficients in the RF signal314 into the reconstructed information 310.

The basis functions may be any suitable orthogonal set or non-orthogonalset of basis functions. For example, the basis functions may be In-Phaseand Quadrature-Phase (I/Q) signals, Fourier basis functions, polynomialbasis functions, Gaussian basis functions, exponential basis functions,wavelet basis functions, or combinations of these and/or other suitableset of basis functions that can be utilized to represent RF waveformsthat are transmitted over a channel. The basis functions may havedifferent phase, amplitude, and/or frequency components. In someimplementations, the basis functions may be parameterized and thetraining may involve optimizing over parameters of the basis functions.

Training the encoder network 302 and decoder network 304 may begin withany suitable set of initial conditions. For example, the training maybegin with a random set of basis functions subject to certainconditions. Alternatively, the training may begin with a fixed set ofbasis functions, such as commonly used RF communication basis functionsincluding Quadrature Phase-Shift Keying (QPSK) or Gaussian BinaryFrequency Shift Keying (GFSK), orthogonal frequency division multipleaccess (OFDM), or other fixed set of basis functions.

During training, the encoder network 302 and decoder network 304 attemptto learn improved basis functions, according to results of encoding anddecoding. Training the encoder 102 and decoder 104 may involveoptimizing over a set of basis functions or over different sets of basisfunctions, for example using greedy search or other optimization-typealgorithm.

In some implementations, the input information 308 may be chosen from atraining set of information. The input information 308 may, in someimplementations, be limited to a particular class of information, suchas binary information, discrete-time information, analog waveforms, orother class of information. In such scenarios, the system 300 will betrained to learn communication encoding and decoding techniques that aretuned to communicate that particular class of information (over aparticular channel or class of channels). By training on different typesof information 308 and different types of channels 306, the system 300may be trained to learn different encoding and decoding operations thatare applicable to different communication scenarios.

The loss function 318 may be any suitable measure, or combination ofmeasures, of distance between the input information 308 and thereconstructed information 310. For example, the loss function 318 mayinclude cross-entropy, mean squared error (MSE), clipped MSE whichpenalizes predicted values according to MSE but only for values whichfall on the wrong side of a decision threshold, or an exponential lossfunction that penalizes loss exponentially, or other suitable distancemetric(s).

In addition, as discussed above, other performance metrics may beincorporated into training, for example as part of the loss function 318and/or as hard constraints, etc. For example, such performance metricsmay include bit error rate (BER) as a function of the signal-to-noiseratio (SNR), communication bandwidth, communication power, spectralefficiency (the number of bits per second that can be transmitted over afixed bandwidth channel at a specific SNR). Any one or combinations ofsuch metrics may be utilized during training as part of the lossfunction 318 (e.g., as a weighted combination) and/or as hardconstraints in addition to the loss function 318.

FIG. 4 is a flowchart illustrating an example method 400 of training anRF system that implements machine-learning encoder and decoder networksto learn encoding and decoding over RF channels. The training method 400may be performed by one or more processors, such as one or more CPUs,GPUs, DSPs, FPGAs, ASICs, TPUs, or neuromorphic chips or vectoraccelerators that execute instructions encoded on a computer storagemedium.

The training method 400 includes determining first information (402),which may be information that is to be communicated over an RF channel.As discussed above, the first information may be any suitablediscrete-time, analog, discrete-valued, or continuous-valuedinformation. For example, in some instances, this input information maybe whitened discrete bits or symbols, or in other cases, the inputinformation may follow the distribution of a non-whitened informationsource. As previously discussed in regards to FIG. 3, above, in someimplementations, the first information may be represented by trainingdata that is utilized for training purposes. In such scenarios, thetraining data may have a different form than the first information, butnonetheless may represent the first information for purposes oftraining.

An encoder machine-learning network is used to process this firstinformation to generate a first RF signal that is to be transmitted overa communication channel (404). As discussed above, in someimplementations the first information may be represented by trainingdata, in which case the encoder machine-learning network processes thetraining data representing the first information. Furthermore, asdiscussed above, the generated first RF signal may represent an analogRF waveform that is transmitted over a channel, or may be anintermediate representation (e.g., samples, basis coefficients,distributions over RF waveforms, etc.) that undergoes further processing(e.g., filtering, D/A conversion, modulation, etc.) to generate ananalog RF waveform. This encoding process may utilize any suitablemapping from an input information space into an RF signal space, asdiscussed in regards to FIG. 3, above.

The training method 400 further includes determining a second RF signalthat represents the first RF signal having been altered by transmissionthrough the communication channel (406). In training scenarios, theeffects of the communication channel may be implemented by a model of achannel obtained by simulation and/or real channel data, or may beimplemented by a real-world communication channel. As discussed above,the second RF signal may represent an analog RF waveform that isreceived over a channel, or may be an intermediate representation (e.g.,samples, basis coefficients, distributions over RF waveforms etc.) thatis a result of processing (e.g., filtering, sampling, equalizing, etc.)a received analog RF waveform.

A decoder machine-learning network is then used to process the receivedRF signal and generate second information as a reconstruction of thefirst information (408). As previously discussed in regards to FIG. 3and in regards to steps 402 and 404, above, in some implementations, thefirst information may have been represented by training data that isutilized for training purposes. In such scenarios, the input trainingdata may have a different form than the original first information, butnonetheless the decoder may generate the second information as areconstruction of the first information that is represented by thetraining data. This decoding process may utilize any suitable mappingfrom an RF signal space into reconstructed information space, asdiscussed in regards to FIG. 3, above.

A measure of distance is calculated between the second information andthe first information (410). This measure of distance may be implementedas a loss function (e.g., loss function 318 in FIG. 3) and may representa difference or error between the original input information and thesecond (reconstructed) information. As examples, the measure of distancemay include cross-entropy, mean squared error, or other geometricdistance metric (e.g., MSE, MAE, KL divergence), or may combine severalgeometric and/or entropy-based distance metrics into an aggregateexpression for distance.

The training method 400 further includes updating at least one of theencoder network or the decoder network based on the measure of distancebetween the second information and the first information (412). Thisupdate may be applied to the encoder network and/or the decoder networkin a joint or iterative manner, or individually, as discussed above. Theupdates may generally include updating any suitable machine-learningnetwork feature of the encoder network and/or decoder network, such asnetwork weights, architecture choice, machine-learning model, or otherparameter or connectivity design, as discussed in regards to FIG. 3,above. As an example, in some implementations, if the encoder networkand/or decoder network are trained to learn a set of basis functions forcommunicating over the RF channel, then the update process may includeupdating the set of basis functions that are utilized in the encodernetwork and/or decoder network.

FIG. 5 illustrates examples of basis functions that may be learned andutilized by an encoder machine-learning network and/or decodermachine-learning network to communicate over RF channels. The examplesin FIG. 5 illustrate four different sets of convolutional basisfunctions that are learned by an encoder for four different values ofdelay spread in a communication channel. However, in general anysuitable form of basis functions may be learned by the encoder networkand/or decoder network.

As shown in FIG. 5, different types of basis functions are learned fordifferent values of delay spread (delay spread values 4, 3, 2, and 1).In these examples, each set of basis functions has two components,although in general any suitable number of basis functions may belearned. In these examples, the encoder has learned to adjust thecompactness of the two basis components depending on the delay spread inthe channel.

Therefore, based on such training, the encoder and/or decoder may bedeployed to utilize different sets of basis functions for differentchannel conditions (e.g., different channel delay spreads) in anadaptive manner. For example, in scenarios where machine-learningnetworks are deployed in a real-world communication system, the systemmay obtain channel state information (CSI) and adjust the encodernetwork and/or decoder network according to the state of the channel.Depending on the state of the channel, the encoder network and/ordecoder network may simply adjust parameters (e.g., transmission power)for the same set of basis functions, or may change the set of basisfunctions entirely (e.g., by switching between the four sets of basisfunctions in FIG. 5). Such updates may also be performed duringdeployment based on simplified encoders and/or decoders that do notutilize full machine-learning networks, but instead utilize simplifiedencoding and/or decoding techniques based on results of training acorresponding encoder machine-learning network and decodermachine-learning network.

FIG. 6 illustrates examples of a transmitted RF signal 612 and areceived RF signal 614 that may be learned by the encoder and decodermachine-learning networks for communicating over an RF channel. Thesignals may correspond to the previously discussed transmitted RF signal312 and received RF signal 314 in FIG. 3, above.

In the examples of FIG. 6, the transmitted RF signal 612 and received RFsignal 614 represent analog RF waveforms that are actually transmittedand received over a channel. For example, the transmitted RF signal 312may be a waveform that is actually transmitted over a communicationmedium, and the received RF signal 314 may be a waveform that isactually received after having undergone impairments over acommunication medium. However, as discussed in regards to FIGS. 1 and 3,above, in general the transmitted RF signals and received RF signalsthat are learned by the encoder and decoder may be any suitablerepresentation (e.g., samples, basis coefficients, etc.) that may befurther processed or transformed into analog RF waveforms.

In the examples of FIG. 6, the RF signals are at 0 dB SNR for 128 bitsof information, and In-phase and Quadrature-phase components are shownfor the transmitted and received RF signals. In general, however, theencoder and decoder machine-learning networks may be trained to learnany suitable form of transmitted and received RF signals, and are notlimited in the number of components in each RF signal.

As shown in FIG. 6, the transmitted RF signal 612 is not immediatelyrecognizable as corresponding to any known modulation scheme that iscurrently used in systems today. For example, the transmitted RF signal612 appears to use at least three common discrete levels, and appears toencode information in some mixture of time and frequency across thesample space.

FIG. 7 illustrates an example of a system 700 with an encoder anddecoder that may be deployed for learned communication of informationover a real-world communication channel. The system 700 includes anencoder 702 and decoder 704 that are deployed to communicate over areal-world channel 706.

The encoder 702 receives input information 708 to be communicated, andmaps the input information 708 into a transmitted RF signal 712. Theencoding mapping that is utilized by the encoder 702 may be designedbased on previous training of a machine-learning network that learnedhow to encode information into RF signals, using the training describedin regards to FIGS. 3 and 4, above. For example, the encoder 702 mayimplement a trained machine-learning network during deployment, or mayimplement a simplified encoding mapping that utilizes results oftraining a machine-learning network, as discussed further below.

As previously discussed, in some implementations, the encoder 702 mayinclude processing (e.g., filtering, modulation, etc.) that generatesthe RF signal 712 as an analog RF waveform for transmission.Alternatively, in other implementations, the encoder 702 may generatethe RF signal 712 as an intermediate representation that is subsequentlyprocessed into an analog RF waveform by additional processing such asfiltering or modulation for transmission over the channel 706.

The decoder 704 receives RF signal 714 that has been impaired by thechannel 706, and maps the received RF signal 714 into reconstructedinformation 710. The decoding mapping that is utilized by decoder 704may be designed based on previous training of a machine-learning networkthat learned how to decode RF signals into reconstructed information,using the training described in regards to FIGS. 3 and 4, above. Forexample, the decoder 704 may implement a trained machine-learningnetwork during deployment, or may implement a simplified decodingmapping that utilizes results of training a machine-learning network, asdiscussed further below

As previously discussed, in some implementations, the decoder 704 mayinclude processing (e.g., filtering, modulation, etc.) that directlyinputs the received RF signal 714 as an analog RF waveform received overthe channel. Alternatively, in other implementations, the decoder 704may process the RF signal as an intermediate representation that resultsfrom prior processing of an analog RF waveform that was received fromthe channel 706.

In some implementations, the encoder 702 and/or decoder 704 may beupdated during deployment, for example by update process 716, based onresults of communication. Such updates may be based on feedbackinformation that is determined based on results of transmission andreconstructions during deployment.

In some implementations, the system 700 may be configured to collectinformation regarding the channel 706 and/or regarding performancemetrics, for example using channel state and performance estimator 718.The estimator 718 may be configured to detect such information, forexample, by detecting a training signal that was transmitted as thetransmitted RF signal 712. The estimator 718 may provide suchinformation via feedback to control various updates to the encoder 702and/or decoder 704 during deployment, as shown in the example of FIG. 7.Such updates may include updating one or more machine-learning features(in scenarios where the encoder 702 and/or decoder 704 implementmachine-learning networks during deployment), or may include updating asimplified encoding and/or decoding mapping that is utilized by theencoder 702 and/or decoder 704 (in scenarios where the encoder 702and/or decoder 704 implement simplified encoding/decoding techniquesbased on previously-trained machine-learning networks).

The feedback that is sent from the channel state and performanceestimator 718 may take any suitable form and may be transmitted on anysuitable time scale. For example, such feedback may be provided based onestimates obtained from the forward link (encoder 702 to decoder 704) orbased on estimates obtained from a reverse link (decoder 704 to encoder702) to estimate the state of the channel and/or estimates ofperformance. The feedback information may vary in size depending onvarious factors, such as the number of modes to choose from, theavailable bandwidth and latency of the feedback channel, and otherconsiderations. In some instances, this feedback information may beencoded into protocol messages within a wireless system.

As an example, the feedback may be generated by the encoder 702transmitting a known training RF signal, and the decoder 704 (and/orother component in the RF receiver) determining the state of the channeland performance measurements based on comparing the received RF signalwith the known transmitted training RF signal. In some implementations,the feedback may only be provided to the receiver to update the decoder704, without necessarily providing the feedback to the transmitter toupdate the encoder 702 (half-model updates).

The conditions of channel 706 may change over different time scales, forexample depending on the type of environment in which the RF signals arecommunicated. For instance, the time scale of variations in the channel706 may depend on whether the environment is rural or urban, whetherenvironmental objects are moving quickly or slowly (e.g., specifyingcoherence time, or correlation time of channel statistics), whether theenvironment is in an aircraft or spacecraft, or whether other radioemitters are located nearby. In some instances where the channelcoherence time is very long or static (e.g., fixed radios andreflectors), encodings may be specifically learned for these impairmentsover long time scale. One example of this might be in a fixed geometryindustrial or urban communications environment.

In some implementations, the conditions present in the channel 706 maybe categorized into a number of different modes. The different modes mayrepresent any suitable categorization of channel conditions, such aslevel of noise, SNR, delay spread, time scale of channel variations,etc. For each of these modes, the encoder 702 and/or decoder 704 mayhave been trained to learn a suitable set of encoding and/or decodingtechniques, as discussed in regards to FIG. 3, above. During deployment,the encoder 702 and/or decoder 704 may be adaptively updated based onthe particular mode of the channel 706 that is estimated. As shown inFIG. 7, in some implementations, a transmission mode controller 720 maybe implemented to decide which mode configuration is to be utilized forthe encoder 702 and/or decoder 704.

The transmission mode controller 720 may utilize feedback from thechannel state and performance estimator 718. As discussed above, suchfeedback may be obtained from the forward and/or reverse link, and maybe provided to the transmission mode controller 720 to help decide whichmode of operation to select at any given time. In this way, the system700 can learn suitable encoding and/or decoding techniques for a rangeof different channel conditions and then adaptively update the encoder702 and/or decoder 704 to select a suitable mode under any given channelcondition.

There are a number of scenarios in which learned communications may beused in real world applications. For example, during training, theencoder 702 and/or decoder 704 may be trained on closed-form analyticmodels of channel 706. Given sufficiently accurate stable analyticmodels of the channel of interest, efficient representations forcommunication across the channel 706 may be learned and used without anyon-line adaptation. Such implementations may be suitable in environmentswhere the real-world channel 706 sufficiently corresponds to analyticmodels, such as channels that vary slowly in time, or are otherwise morestable and predictable.

As another example, in scenarios where channels vary more unpredictablyin the real world, such as depending on deployment location, conditions,or nearby effects, the system 700 may perform on-line adaptation andon-line learning of specialized encoding and/or decoding techniques thatperform well for the given real world deployment scenario. In suchimplementations, updates to the encoder 702 and/or decoder 704 may beperformed during deployment, based on real-world measurements of thechannel and/or system performance. Such updates may be performed basedon results of objective-achieving strategies that were learned inregards to training in FIGS. 3 and 4, above.

However, if the real-world feedback does not lend itself to exactanalytic expression for the channel transform, then the update process716 may utilize approximations, rather than exact analytic solutions, todetermine updates for the encoder 702 and/or decoder 704. For example,in implementations where gradients of an objective function arecomputed, then approximate gradients may be computed, rather than exactderivative calculations. Furthermore, in real-world scenarios, theupdate process 716 may additionally consider real-world factors, such ascommunications cost, latency, and capacity of the feedback channel fromthe channel state and performance estimator 718. In general, moreaccurate and more extensive feedback allows for updates that are moreeffective by the update process 716, but at the cost of communications,latency, and bandwidth. Therefore, in deployment scenarios where theencoder 702 and/or decoder 704 are updated based on feedbackinformation, such additional considerations may be factored into theupdate process 716.

In some implementations, the encoder 702 and/or decoder 704 may utilizesimplified forms of encoding and/or decoding mappings that were learnedduring training. For example, the encoder 702 may utilize a simplifiedlookup table to generate the transmitted RF signal 712 based on theinput information 708. Analogously, in some implementations, the decoder704 may generate the reconstructed information 710 from the received RFsignal 714 by utilizing a distance-based decoding technique, or othersimplified decoding technique that is based on a more general decodingmapping learned during training, or that is based on an encoder mappingthat was learned during training.

As a specific example of such simplified deployment, in someimplementations, during training, an encoder machine-learning networkmay learn a mapping from input information 708 to RF signals 712. Themapping may be, for example, a signal constellation that representsdifferent RF signals 712 as different points in the constellationcorresponding to particular inputs 708. However, during deployment, theencoder 702 may utilize a simplified lookup-table (LUT) to map inputinformation 708 to points on the constellation to generate the RF signal712, based on the training results of the encoder machine-learningnetwork. Analogously, the decoder 704 may utilize simplified decodingalgorithms (e.g., distance-based decoding algorithms) that are based onresults of training a decoder machine-learning network, or based on acounterpart trained encoder machine-learning network.

In such scenarios, the encoder 702 and/or decoder 704 may be trained(e.g., as an autoencoder) for system design during training, butapproximations or compact look up tables may be utilized, in the encoder702 and/or the decoder 704, to deploy and implement the system 700 inreal-world applications. As such, in some implementations, the encoder702 and decoder 704 that are implemented in a deployed system may notimplement a full machine-learning network, but instead may utilizeresults of encoding and decoding mappings that were learned bymachine-learning networks during training. In some cases, these learnedmappings from a neural network may already form very compact andefficient tensor computation expressions which can be deployedefficiently into a baseband processor.

FIG. 8 is a flowchart illustrating an example method 800 of deploying anencoder and decoder to perform learned communication over a real-worldRF channel. Such deployment may utilize encoding and decoding techniquesthat were previously learned by machine-networks during trained, forexample by using training techniques discussed in regards to FIGS. 3 and4, above, or similar training techniques.

The method 800 includes determining an encoder and a decoder, at leastone of which implements an encoding or decoding that is based on atleast one of an encoder machine-learning network or a decodermachine-learning network that has been trained to encode or decodeinformation over a communication channel (802). In some scenarios, thedeployed encoder and/or decoder may implement machine-learning networksthat were previously trained. Alternatively, in other scenarios, theencoder and/or decoder may utilize simplified encoding/decoding mappingsthat are based on results of previously training an encodermachine-learning network and/or decoder machine-learning network, asdiscussed in regards to FIG. 7, above.

The method 800 further includes determining first information (804). Asdiscussed above, the first information may be any suitablediscrete-time, analog, discrete-valued, or continuous-valuedinformation.

The encoder is then used to process this first information to generate afirst RF signal (806). As discussed above, the first RF signal mayrepresent an analog RF waveform that is transmitted over a channel, ormay be an intermediate representation (e.g., samples, basiscoefficients, etc.) that undergoes further processing (e.g., filtering,D/A conversion, modulation, etc.) to generate an analog RF waveform.This encoding process may utilize any suitable mapping, or simplifiedform of a mapping, from an input information space into an RF signalspace that was learned during training an encoder machine-learningnetwork, for example using training techniques discussed in regards toFIG. 3, above.

The method 800 further includes transmitting, using at least onetransmitter, the first RF signal, through a communication channel (808).As discussed in regards to step 806, above, transmission of the first RFsignal may involve directly transmitting the first RF signal itself(e.g., if the encoder has generated the first RF signal as an analog RFwaveform suitable for transmission over the channel), or may involveprocessing the first RF signal to convert it into an analog RF waveformfor transmission (e.g., using filtering, D/A conversion, modulation,etc.). The transmission may utilize any suitable transmission techniquewhich may include other features or parameters, for example using singleor multiple antennas, adaptive power control, etc.

The method 800 further includes receiving a second RF signal thatrepresents the first RF signal having been altered by transmissionthrough the communication channel (810). In deployment scenarios, thecommunication is in a real-world channel (in contrast to trainingscenarios of FIGS. 3 and 4, where the channel may be a simulated channelor real-world channel). As discussed above, the second RF signal mayrepresent an analog RF waveform that is received over a channel, or maybe an intermediate representation (e.g., samples, basis coefficients,etc.) that is a result of processing (e.g., filtering, sampling,equalizing, etc.) a received analog RF waveform.

A decoder is then used to process the received second RF signal andgenerate second information as a reconstruction of the first information(812). This decoding process may utilize any suitable mapping, orsimplified form of a mapping, from an RF signal space into reconstructedinformation space that was learned by a decoder machine-learning networkduring training, for example using training techniques discussed inregards to FIG. 3, above.

As discussed in regards to FIG. 7, above, in some implementations, adeployed system may further utilize the received second RF signal(and/or other information resulting from the communication) to generatefeedback and update the encoder and/or the decoder.

Furthermore as discussed in regards to FIG. 7, above, in someimplementations, the encoder and/or decoder may utilize simplified formsof encoding and/or decoding mappings that were learned during training.For example, the encoder may utilize a simplified lookup table togenerate the first RF signal based on the first information.Furthermore, in some implementations, the decoder may utilize adistance-based decoding technique, or other simplified decodingtechnique that is based on a more general decoding mapping that waslearned during training, or that is based on the encoder mapping thatwas learned during training. As such, in some implementations, theencoder and decoder that are implemented in a deployed system may notimplement a full machine-learning network, but instead may utilizeresults of encoding and decoding mappings that were learned bymachine-learning networks during training.

FIG. 9 is a diagram illustrating an example of a computing system thatmay be used to implement one or more components of a system thatperforms learned communication over RF channels.

The computing system includes computing device 900 and a mobilecomputing device 950 that can be used to implement the techniquesdescribed herein. For example, one or more parts of an encodermachine-learning network system or a decoder machine-learning networksystem could be an example of the system 900 described here, such as acomputer system implemented in any of the machine-learning networks,devices that access information from the machine-learning networks, or aserver that accesses or stores information regarding the encoding anddecoding performed by the machine-learning networks.

The computing device 900 is intended to represent various forms ofdigital computers, such as laptops, desktops, workstations, personaldigital assistants, servers, blade servers, mainframes, and otherappropriate computers. The mobile computing device 950 is intended torepresent various forms of mobile devices, such as personal digitalassistants, cellular telephones, smart-phones, mobile embedded radiosystems, radio diagnostic computing devices, and other similar computingdevices. The components shown here, their connections and relationships,and their functions, are meant to be examples only, and are not meant tobe limiting.

The computing device 900 includes a processor 902, a memory 904, astorage device 906, a high-speed interface 908 connecting to the memory904 and multiple high-speed expansion ports 910, and a low-speedinterface 912 connecting to a low-speed expansion port 914 and thestorage device 906. Each of the processor 902, the memory 904, thestorage device 906, the high-speed interface 908, the high-speedexpansion ports 910, and the low-speed interface 912, are interconnectedusing various busses, and may be mounted on a common motherboard or inother manners as appropriate. The processor 902 can process instructionsfor execution within the computing device 900, including instructionsstored in the memory 904 or on the storage device 906 to displaygraphical information for a GUI on an external input/output device, suchas a display 916 coupled to the high-speed interface 908. In otherimplementations, multiple processors and/or multiple buses may be used,as appropriate, along with multiple memories and types of memory. Inaddition, multiple computing devices may be connected, with each deviceproviding portions of the operations (e.g., as a server bank, a group ofblade servers, or a multi-processor system). In some implementations,the processor 902 is a single-threaded processor. In someimplementations, the processor 902 is a multi-threaded processor. Insome implementations, the processor 902 is a quantum computer.

The memory 904 stores information within the computing device 900. Insome implementations, the memory 904 is a volatile memory unit or units.In some implementations, the memory 904 is a non-volatile memory unit orunits. The memory 904 may also be another form of computer-readablemedium, such as a magnetic or optical disk.

The storage device 906 is capable of providing mass storage for thecomputing device 900. In some implementations, the storage device 906may be or include a computer-readable medium, such as a floppy diskdevice, a hard disk device, an optical disk device, or a tape device, aflash memory or other similar solid-state memory device, or an array ofdevices, including devices in a storage area network or otherconfigurations. Instructions can be stored in an information carrier.The instructions, when executed by one or more processing devices (forexample, processor 902), perform one or more methods, such as thosedescribed above. The instructions can also be stored by one or morestorage devices such as computer- or machine-readable mediums (forexample, the memory 904, the storage device 906, or memory on theprocessor 902). The high-speed interface 908 manages bandwidth-intensiveoperations for the computing device 900, while the low-speed interface912 manages lower bandwidth-intensive operations. Such allocation offunctions is an example only. In some implementations, the high-speedinterface 908 is coupled to the memory 904, the display 916 (e.g.,through a graphics processor or accelerator), and to the high-speedexpansion ports 910, which may accept various expansion cards (notshown). In the implementation, the low-speed interface 912 is coupled tothe storage device 906 and the low-speed expansion port 914. Thelow-speed expansion port 914, which may include various communicationports (e.g., USB, Bluetooth, Ethernet, wireless Ethernet) may be coupledto one or more input/output devices, such as a keyboard, a pointingdevice, a scanner, or a networking device such as a switch or router,e.g., through a network adapter.

The computing device 900 may be implemented in a number of differentforms, as shown in the figure. For example, it may be implemented as astandard server 920, or multiple times in a group of such servers. Inaddition, it may be implemented in a personal computer such as a laptopcomputer 922. It may also be implemented as part of a rack server system924. Alternatively, components from the computing device 900 may becombined with other components in a mobile device (not shown), such as amobile computing device 950. Each of such devices may include one ormore of the computing device 900 and the mobile computing device 950,and an entire system may be made up of multiple computing devicescommunicating with each other.

The mobile computing device 950 includes a processor 952, a memory 964,an input/output device such as a display 954, a communication interface966, and a transceiver 968, among other components. The mobile computingdevice 950 may also be provided with a storage device, such as amicro-drive or other device, to provide additional storage. Each of theprocessor 952, the memory 964, the display 954, the communicationinterface 966, and the transceiver 968, are interconnected using variousbuses, and several of the components may be mounted on a commonmotherboard or in other manners as appropriate.

The processor 952 can execute instructions within the mobile computingdevice 950, including instructions stored in the memory 964. Theprocessor 952 may be implemented as a chipset of chips that includeseparate and multiple analog and digital processors. The processor 952may provide, for example, for coordination of the other components ofthe mobile computing device 950, such as control of user interfaces,applications run by the mobile computing device 950, and wirelesscommunication by the mobile computing device 950.

The processor 952 may communicate with a user through a controlinterface 958 and a display interface 956 coupled to the display 954.The display 954 may be, for example, a TFT (Thin-Film-Transistor LiquidCrystal Display) display or an OLED (Organic Light Emitting Diode)display, or other appropriate display technology. The display interface956 may include appropriate circuitry for driving the display 954 topresent graphical and other information to a user. The control interface958 may receive commands from a user and convert them for submission tothe processor 952. In addition, an external interface 962 may providecommunication with the processor 952, so as to enable near areacommunication of the mobile computing device 950 with other devices. Theexternal interface 962 may provide, for example, for wired communicationin some implementations, or for wireless communication in otherimplementations, and multiple interfaces may also be used.

The memory 964 stores information within the mobile computing device950. The memory 964 can be implemented as one or more of acomputer-readable medium or media, a volatile memory unit or units, or anon-volatile memory unit or units. An expansion memory 974 may also beprovided and connected to the mobile computing device 950 through anexpansion interface 972, which may include, for example, a SIMM (SingleIn Line Memory Module) card interface. The expansion memory 974 mayprovide extra storage space for the mobile computing device 950, or mayalso store applications or other information for the mobile computingdevice 950. Specifically, the expansion memory 974 may includeinstructions to carry out or supplement the processes described above,and may include secure information also. Thus, for example, theexpansion memory 974 may be provided as a security module for the mobilecomputing device 950, and may be programmed with instructions thatpermit secure use of the mobile computing device 950. In addition,secure applications may be provided via the SIMM cards, along withadditional information, such as placing identifying information on theSIMM card in a non-hackable manner.

The memory may include, for example, flash memory and/or NVRAM memory(non-volatile random access memory), as discussed below. In someimplementations, instructions are stored in an information carrier suchthat the instructions, when executed by one or more processing devices(for example, processor 952), perform one or more methods, such as thosedescribed above. The instructions can also be stored by one or morestorage devices, such as one or more computer- or machine-readablemediums (for example, the memory 964, the expansion memory 974, ormemory on the processor 952). In some implementations, the instructionscan be received in a propagated signal, for example, over thetransceiver 968 or the external interface 962.

The mobile computing device 950 may communicate wirelessly through thecommunication interface 966, which may include digital signal processingcircuitry where necessary. The communication interface 966 may providefor communications under various modes or protocols, such as GSM voicecalls (Global System for Mobile communications), SMS (Short MessageService), EMS (Enhanced Messaging Service), or MMS messaging (MultimediaMessaging Service), CDMA (code division multiple access), TDMA (timedivision multiple access), PDC (Personal Digital Cellular), WCDMA(Wideband Code Division Multiple Access), CDMA2000, or GPRS (GeneralPacket Radio Service), LTE, 5G/6G cellular, among others. Suchcommunication may occur, for example, through the transceiver 968 usinga radio frequency. In addition, short-range communication may occur,such as using a Bluetooth, Wi-Fi, or other such transceiver (not shown).In addition, a GPS (Global Positioning System) receiver module 970 mayprovide additional navigation- and location-related wireless data to themobile computing device 950, which may be used as appropriate byapplications running on the mobile computing device 950.

The mobile computing device 950 may also communicate audibly using anaudio codec 960, which may receive spoken information from a user andconvert it to usable digital information. The audio codec 960 maylikewise generate audible sound for a user, such as through a speaker,e.g., in a handset of the mobile computing device 950. Such sound mayinclude sound from voice telephone calls, may include recorded sound(e.g., voice messages, music files, etc.) and may also include soundgenerated by applications operating on the mobile computing device 950.

The mobile computing device 950 may be implemented in a number ofdifferent forms, as shown in the figure. For example, it may beimplemented as a cellular telephone 980. It may also be implemented aspart of a smart-phone 982, personal digital assistant, or other similarmobile device.

The term “system” as used in this disclosure may encompass allapparatus, devices, and machines for processing data, including by wayof example a programmable processor, a computer, or multiple processorsor computers. A processing system can include, in addition to hardware,code that creates an execution environment for the computer program inquestion, e.g., code that constitutes processor firmware, a protocolstack, a database management system, an operating system, or acombination of one or more of them.

A computer program (also known as a program, software, softwareapplication, script, executable logic, or code) can be written in anyform of programming language, including compiled or interpretedlanguages, or declarative or procedural languages, and it can bedeployed in any form, including as a standalone program or as a module,component, subroutine, or other unit suitable for use in a computingenvironment. A computer program does not necessarily correspond to afile in a file system. A program can be stored in a portion of a filethat holds other programs or data (e.g., one or more scripts stored in amarkup language document), in a single file dedicated to the program inquestion, or in multiple coordinated files (e.g., files that store oneor more modules, sub programs, or portions of code). A computer programcan be deployed to be executed on one computer or on multiple computersthat are located at one site or distributed across multiple sites andinterconnected by a communication network.

Computer readable media suitable for storing computer programinstructions and data include all forms of non-volatile or volatilememory, media and memory devices, including by way of examplesemiconductor memory devices, e.g., EPROM, EEPROM, and flash memorydevices; magnetic disks, e.g., internal hard disks or removable disks ormagnetic tapes; magneto optical disks; and CD-ROM and DVD-ROM disks. Theprocessor and the memory can be supplemented by, or incorporated in,special purpose logic circuitry. Sometimes a server is a general-purposecomputer, and sometimes it is a custom-tailored special purposeelectronic device, and sometimes it is a combination of these things.

Implementations can include a back end component, e.g., a data server,or a middleware component, e.g., an application server, or a front endcomponent, e.g., a client computer having a graphical user interface ora Web browser through which a user can interact with an implementationof the subject matter described in this specification, or anycombination of one or more such back end, middleware, or front endcomponents. The components of the system can be interconnected by anyform or medium of digital data communication, e.g., a communicationnetwork. Examples of communication networks include a local area network(“LAN”) and a wide area network (“WAN”), e.g., the Internet.

The features described can be implemented in digital electroniccircuitry, or in computer hardware, firmware, software, or incombinations of them. The apparatus can be implemented in a computerprogram product tangibly embodied in an information carrier, e.g., in amachine-readable storage device, for execution by a programmableprocessor; and method steps can be performed by a programmable processorexecuting a program of instructions to perform functions of thedescribed implementations by operating on input data and generatingoutput. The described features can be implemented advantageously in oneor more computer programs that are executable on a programmable systemincluding at least one programmable processor coupled to receive dataand instructions from, and to transmit data and instructions to, a datastorage system, at least one input device, and at least one outputdevice. A computer program is a set of instructions that can be used,directly or indirectly, in a computer to perform a certain activity orbring about a certain result. A computer program can be written in anyform of programming language, including compiled or interpretedlanguages, and it can be deployed in any form, including as astand-alone program or as a module, component, subroutine, or other unitsuitable for use in a computing environment.

While this disclosure contains many specific implementation details,these should not be construed as limitations on the scope of anyinvention or of what may be claimed, but rather as descriptions offeatures that may be specific to particular implementations ofparticular inventions. Certain features that are described in thisdisclosure in the context of separate implementations can also beimplemented in combination in a single implementation. Conversely,various features that are described in the context of a singleimplementation can also be implemented in multiple implementationsseparately or in any suitable subcombination. Moreover, althoughfeatures may be described above as acting in certain combinations andeven initially claimed as such, one or more features from a claimedcombination can in some cases be excised from the combination, and theclaimed combination may be directed to a subcombination or variation ofa subcombination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. In certain circumstances, multitasking and parallel processingmay be advantageous. Moreover, the separation of various system modulesand components in the implementations described above should not beunderstood as requiring such separation in all implementations, and itshould be understood that the described program components and systemscan generally be integrated together in a single software product orpackaged into multiple software products.

What is claimed is:
 1. A method of transmitting and receivinginformation through a communication channel, the method comprising:determining an encoder and a decoder, at least one of which implements arespective encoding or decoding based on a corresponding encodermachine-learning network or a decoder machine-learning network that hasbeen trained, by determining a rate of change of an objective functionrelative to variations in the encoder machine-learning network or thedecoder machine-learning network upon processing one or more trainingsignals, to respectively encode or decode information over acommunication channel; determining first information; using the encoderto process the first information and generate a first radio frequency(RF) signal; transmitting, by at least one transmitter, the first RFsignal through the communication channel; receiving, by at least onereceiver, a second RF signal that represents the first RF signal alteredby transmission through the communication channel; and using the decoderto process the second RF signal and generate second information as areconstruction of the first information.
 2. The method of claim 1,further comprising: determining feedback information that indicates atleast one of (i) a measure of distance between the second informationand the first information, or (ii) channel state information regardingthe communication channel; and updating at least one of the encoder orthe decoder based on the feedback information.
 3. The method of claim 2,wherein updating at least one of the encoder or the decoder based on thefeedback information further comprises: determining a channel mode, fromamong a plurality of channel modes, that represents a state of thecommunication channel based on the feedback information; and updating atleast one of the encoder or the decoder based on the channel mode of thecommunication channel.
 4. The method of claim 3, wherein the pluralityof channel modes corresponds to channel conditions including one or moreof level of noise, signal-to-noise ratio (SNR), delay spread, or timescale of channel variations.
 5. The method of claim 4, wherein the timescale of channel variations is based on one or more of a characteristicof a channel environment, a speed of movement of environmental objects,or location of additional radio emitters in a neighborhood of thechannel.
 6. The method of claim 5, wherein the characteristic of thechannel environment includes whether the environment is rural, urban, orin a spacecraft, and wherein the speed of movement of environmentalobjects corresponds to channel coherence time or correlation time ofchannel statistics.
 7. The method of claim 3, wherein determining thechannel mode and updating at least one of the encoder or the decoderbased on the channel mode comprises: providing the feedback informationto a transmission mode controller; selecting, by the transmission modecontroller, the channel mode from the plurality of channel modes basedat least on the feedback information; and updating the encoder or thedecoder using a respective set of encoding or decoding techniques thatcorrespond to the selected channel mode.
 8. The method of claim 1,wherein the encoder implements an encoding mapping that is based onresults of training an encoder machine-learning network and the decoderimplements a decoding mapping that is based on results of training adecoder machine- learning network, wherein the encoder machine-learningnetwork and the decoder machine-learning network have been jointlytrained as an auto-encoder to learn communication over a communicationchannel.
 9. The method of claim 1, further comprising: processing thefirst RF signal to generate a first analog RF waveform; using one ormore transmit antennas to transmit the first analog RF waveform over thecommunication channel; using one or more receive antennas to receive asecond analog RF waveform that represents the first analog RF waveformhaving been altered by the communication channel; and processing thesecond analog RF waveform to generate the second RF signal.
 10. Themethod of claim 1, wherein determining the rate of change of theobjective function upon processing one or more training signalscomprises: determining a measure of distance between an input trainingsignal and an output training signal that corresponds to arepresentation of the input training signal altered by transmissionthrough a communication channel model; and determining the objectivefunction using the measure of distance.
 11. The method of claim 1,wherein processing the first information using the encoder to generatethe first RF signal comprises: accessing, by the encoder, a lookup tablethat corresponds to encoding mappings learned during training theencoder using the encoder machine-learning network; and mapping thefirst information to the first RF signal using the lookup table.
 12. Asystem comprising: at least one processor; and at least one computermemory coupled to the at least one processor having stored thereoninstructions which, when executed by the at least one processor, causethe at least one processor to perform operations comprising: determiningan encoder and a decoder, at least one of which implements a respectiveencoding or decoding based on a corresponding encoder machine-learningnetwork or a decoder machine-learning network that has been trained, bydetermining a rate of change of an objective function relative tovariations in the encoder machine-learning network or the decodermachine-learning network upon processing one or more training signals,to respectively encode or decode information over a communicationchannel; determining first information; using the encoder to process thefirst information and generate a first RF signal; transmitting, by atleast one transmitter, the first RF signal through the communicationchannel; receiving, by at least one receiver, a second RF signal thatrepresents the first RF signal altered by transmission through thecommunication channel; and using the decoder to process the second RFsignal and generate second information as a reconstruction of the firstinformation.
 13. The system of claim 12, wherein the operations furthercomprise: determining feedback information that indicates at least oneof (i) a measure of distance between the second information and thefirst information, or (ii) channel state information regarding thecommunication channel; and updating at least one of the encoder or thedecoder based on the feedback information.
 14. The system of claim 13,wherein updating at least one of the encoder or the decoder based on thefeedback information further comprises: determining a channel mode, fromamong a plurality of channel modes, that represents a state of thecommunication channel based on the feedback information; and updating atleast one of the encoder or the decoder on the channel mode of thecommunication channel.
 15. The system of claim 14, wherein the pluralityof channel modes corresponds to channel conditions including one or moreof level of noise, signal-to-noise ratio (SNR), delay spread, or timescale of channel variations.
 16. The system of claim 15, wherein thetime scale of channel variations is based on one or more of acharacteristic of a channel environment, a speed of movement ofenvironmental objects, or location of additional radio emitters in aneighborhood of the channel.
 17. The system of claim 16, wherein thecharacteristic of the channel environment includes whether theenvironment is rural, urban, or in a spacecraft, and wherein the speedof movement of environmental objects corresponds to channel coherencetime or correlation time of channel statistics.
 18. The system of claim14, wherein determining the channel mode and updating at least one ofthe encoder or the decoder based on the channel mode comprises:providing the feedback information to a transmission mode controller;selecting, by the transmission mode controller, the channel mode fromthe plurality of channel modes based at least on the feedbackinformation; and updating the encoder or the decoder using a respectiveset of encoding or decoding techniques that correspond to the selectedchannel mode.
 19. The system of claim 13, wherein the encoder implementsan encoding mapping that is based on results of training an encodermachine-learning network and the decoder implements a decoding mappingthat is based on results of training a decoder machine- learningnetwork, wherein the encoder machine-learning network and the decodermachine-learning network have been jointly trained as an auto-encoder tolearn communication over a communication channel.
 20. The system ofclaim 13, wherein the operations further comprise: processing the firstRF signal to generate a first analog RF waveform; using one or moretransmit antennas to transmit the first analog RF waveform over thecommunication channel; using one or more receive antennas to receive asecond analog RF waveform that represents the first analog RF waveformhaving been altered by the communication channel; and processing thesecond analog RF waveform to generate the second RF signal.
 21. Thesystem of claim 12, wherein determining the rate of change of theobjective function upon processing one or more training signalscomprises: determining a measure of distance between an input trainingsignal and an output training signal that corresponds to arepresentation of the input training signal altered by transmissionthrough a communication channel model; and determining the objectivefunction using the measure of distance.
 22. The system of claim 12,wherein processing the first information using the encoder to generatethe first RF signal comprises: accessing, by the encoder, a lookup tablethat corresponds to encoding mappings learned during training theencoder using the encoder machine-learning network; and mapping thefirst information to the first RF signal using the lookup table.
 23. Atleast one non-transitory computer-readable medium storing instructionsthat, when executed, cause at least one processor to perform operationscomprising: determining an encoder and a decoder, at least one of whichis configured to implements a respective encoding or decoding that isbased on at least one of an a corresponding encoder machine-learningnetwork or a decoder machine-learning network that has been trained, bydetermining a rate of change of an objective function relative tovariations in the encoder machine-learning network or the decodermachine-learning network upon processing one or more training signals,to respectively encode or decode information over a communicationchannel; determining first information; using the encoder to process thefirst information and generate a first RF signal; transmitting, by atleast one transmitter, the first RF signal through the communicationchannel; receiving, by at least one receiver, a second RF signal thatrepresents the first RF signal altered by transmission through thecommunication channel; and using the decoder to process the second RFsignal and generate second information as a reconstruction of the firstinformation.